Adjustable-core transformer



Jan. 17,1928. 1,656,381

O. E. MARVEL ADJUSTABLE GORE TRANSFORMER Filed June 5, 1923 2f f' ff.

6 /4 INVENTOR,

44; ATTORNEY;n

Uff

Patented Jan. 17, 1928.

UNITED STATES 1,656,381 PATENT OFFICE.

GRIN' E. MARVEL, 0F

Y PANY,

DAYTON, OHIO, ASSIGNOR T THE DAY-FAN ELECTRIC COM- OF DAYTON, OHIO, ACORPORATION OF OHIO.

ADJUSTABLE-CORE TBANSFOBMER.

Application med Inne S, 1923. Serial No. 643,543.

This invention relates to a device for the transferoof high frequencyelectrical energy from one circuit to another as from the late circuitof a. vacuum tube to the gri or 6 control circuit of the followin tube.

It is one of the rineipal o jects of my invention to provi e atransformer with variable inductance and` impedance, so that thetransformer will transfer this hi frequency energy at its maximum eciency over a band of frequencies. The band of fr uen'cies that thetransformer will cover isedetermined by the number of turns of wire ofthe primary and secondary windings andthe iron core. The ltransfer ofenergy of thetransformer with a given number of turns in the primary andsecondary windin band of frequencies, amount of the iron core that linksin the path of the magnetic flux set up by the cur-V rent flowingthrough the primary and secondary windings of the transformer.

y It is another object of my invention to provide a means of actuatingthe movable iron core in such a manner that it will change theinductance and impedance of the transformer over the band of frequenciesfor which the transformer may be designed. It is another pur cse of myinvention to provide a means of eeping the potential of the iron core atzero with respect to the negative or common side of the electricalcircuits.

It is still another object of my invention to provide a means ofaccelerating the dissiation of the electrical charge of the capacity ofthe primar and secondary windings, upon the reversa of the cycle of theelectrical ener which is being transferred from one circuit to another.

It is a further object of my invention to provide a method of windingthe rimary and secondary coils so that they wil have a smalldistributedcapacity between their ends and the proper amount of capacity betweenthe rimary and' secondary windings for an efiicient transfer of highfrequency energy over a given band of fre uencies.

In the accom anying crawings, Figure 4is a longitudina sectional view ofmy transformer, taken on the line 1-1 of Figure 3. Figure 2 is-a sideelevational view of the same, partly in section, illustratingdiagrammatically the method of winding the priefficiency of the and ironcore for a given' will depend upon the mary and secondary wires. Firure3 is a cross sectional view taken through the transformer on the line3-3 of Figure 1. And Fig. 4 is a schematic diagram illustrating oneapplication of my transformer.

Throughout the specification and drawings, similar referencecharacters'denote corresponding parts.

In the accompanying drawings illustrating one form of embodiment of myinvention, the numeral 1 designates an elongated cylindrical lcasingmade of non-conductive electrical material such as bakelite or specialradio fiber.

Formed on the rear end of the casing 1 is an annular Harige 2, and onits middle portion there is an integral annular flange 3. Between theseflanges the casing 1 forms a bobbin to receive a primary winding 4 anda. secondary winding 5. The primary winding 4 is connected between'binding posts 6 and 7 on the flanges 2 and 3 respectively, while thesecondary `winding is connected between binding posts 8 and 9 on thesame flanges. (See Figure 2.) These windings are layer Wound on thecasing 1, without doubling back on any turn. This method of windinggives a small distributed capacity and the proper amount of capacitybetween the primary and secondary windings for an efficient transfer ofhigh frequency energy over a given band of frequencies.

Longtudinally movable into and out of the wound part of the casing 1, isa nonmagnetic split sleeve 10 preferably of cop er whose interior islined with suitable insuliting material 11 which surrounds a laminatedcore 12 made up of very thin strips of high frequency iron. (See Figure3.)

Suitably secured to the front end of the sleeve 10, for the purpose ofmoving it longitudinally within the casing 1, is a rod 13 which carrieson its front end a knurled knob 14. This rod is calibrated for desiredwave lengths by having provided on its rear portion graduations 15corresponding to those wave lengths. A desired wave length Vmay bereadily selected by moving the rod to a position wherein a graduation 15desig nating that wave length is in alinement with the front end of thecasing 1. The rod 13 thus provides 'a selective and convenient means forchanging the position of the iron core containing-sleeve 10 within thewound part of the casing 1 to change the inductance 11 andim dance ofthe transformer over the l band 'o fre uencies for which it is designed,

v radial hole which extends through the casing 1, to receive a screw 16whose inner portion is hollow to contain a helical spring 17 whichpressesa carbon brush 18 intoengagement with the iron corecontaining-sleeve 10. A wire 19 connects the screw 16 with thesecondarywire so that the brush 18 will ground the sleeve 10, thereby'tending toIilntaintaiiithe sleeve and secondary filament u i for radio purposesThe urpose of this is to accelerate the dissi ation of theelectricalcharge of the capaci y of the primaryand secondary windings,upon the ref vers'al of the cycle of the electrical energy beinAtransferred Ifrom one circuit to another. dapted to be slipped over theflanges-2,- and 3, behind a fronti-lange 20 on the casing l, is a cap orshell 21 to cover the primary and secondary windings. This cap ma bereadily ap hed and removed.

salready sta the present invention relates primarily to the transferlofhigh fre-V quency electrical energy from one circuit to another, and isparticularly applicable for use 4in airadio reiver,i orflike apparatus,ein loying vacuum tubes for amplifying hig frequency energyoscillations. In such apparatus high frequency energy oscillations aretransferred from the plate or output circuit of one vacuum tube to thegrid or in ut circuit of the next succeeding vacuum tu said circuitsbeing coupled in energy transmitting relation with one another. Suchcoupling may be effected by means of the transformer herein described,the rimary winding 4 being connected in the ate circuit of the first'vacuum tube an the secondary winding 5 being connected in the 'gridcircuit of the second vacuum tube. The connection of the transformer insuch energy4 transferring relationship between the late and gridcircuits asfjust describedis illustrated inthe schematic diagram of Fi 4which shows the conventional and we arrangement of circuits forconnect-4 ing one vacuum tubel with the next v`succeeding vacuum tube.31. `1n this.arrange ment, the plate circuit 320i the first vacuumwinding 4 o w ich is iii the plate circuit 82 [the tube 31 .thro h theseconda tube 30 is cou lcd with the input or grid: circuit 33 of csecond vacuum tube 31 in the 4usual wa `b a transformer, the primary4and the secondary windiizi 5 of which is in circuit 33,'whi lattercircuit, it

the 'd willgobserved, extends from the grid of windn 5 to thelament othe tube 31'. at portion .of the grid circuit 33 which is between the,up

5 andthe-filamentof the tube 31 und potential when the transformer is-is changed rom which it follows that is, because of its interrelationwith other circuits not herein illustrated, commonly said to be on thenegative or common side of the circuit. The sleeve 10 of the transformeris connected with or ounded to that terminal of the secondary winding,`5 which lis connected to the negative or common side of the circuit andhence the sleeve is at the same potential as this side of the circuit.

Iii the operation o f an apparatus as described, when it is desired totransmit oscillations of itV iven frequency or wave length from thepliite circuit 32 to the grid circuit 33, the iron core 12 of thetransformer. is moved to the position which will insure the mosteffective transfer of iener from the primary winding 4 to the secon arywinding 5, the proper position for the core being indicated by thecalibrations on the stem 13.

lVlien it is desired to transmit oscillations of a different frequencythe position of the core 12 is changed in accordance with thecalibrations 4on the stem 13 so as to again obtain the most electivetransfer of theenergy. By adjusting the iron core in this manneptheamount-of iron that links with the magnetic` fields of the rimary andsecondary windin e inductance and impedance of these windings alsochange with the position ofthe iron core' within'the windings. FromV theforegoing it will be ap arent that the movement o the core 12 within thewindings results not only in a variation of the impedances of thewindings but also in a simu taneous .varia tion of the impedances of theplate'and grid circuits in which they are connected, and hence themovement ofthe iron core constitutes a simple means for tuning thesecircuits for the most effective and eilicient transfer of energy betweenthem. The p ose of splitting the copper sleeve 10 as s own in the drawinis to, prevent the formation of undesirab e eddy currents which tend toneutralize the action of the windings and to hinder the proper transferof energy between the windings. Another advanta e of the resentinvention is that it rovi es means or effecting sharp o 'theapparatus 1. A transformer comprising a casing, a primary and asecondary surround. ing the latter, a non-nagnetic split lsleeve movablein said casing, an iron core within gie sleeve, and means for vgroundingsaid4 2. A transformer comprising a hollow bobbin formed of insulatingmaterial, ri-

mary and seconV '.win diy in inductivel eoupl relatie with one another aut said jbohb' 'an means for manually changing the in uctance andimpedante of the transformer, said means disposed bobbin comprisingmag-- netic means magnetically coupled with both of said windinnon-magnetic conducting means dispose to have capacity coupling withboth of said windings, and means for grounding said non-magnetic means.

3. A transformer comprising a casing, a

rimary and asecondary winding surrounding the latter, a non-magneticsleeve movable in said casing, a brush in contact with the sleeve, ahousing in said casing for the brush, and a wire connected between saidhousing and the secondary winding for 'the purpose specified.

4, A transformer comprising a casing,l a primary and a secondary windingsurroundtlie latter, a non-magnetic sleeve movab e in said casing, saidcasing containing a radial hole, a hollow screw in the latter,a helicalspring contained within said screw, a 4brush also in said screw adaptedto. be forced into engagement with the sleeve by the spring, and a wireconnected between said screw and the secondary winding for the purposespecified.

5. Av transformer oomprisin concentrically disposed primary and secon arwindings a non-magnetic sleeve disposed a jacent said windings andlongitudinally movable relative thereto, and conducting means connectedbetween said sleeve and one of said windings, to ground the former.

6. A transformer adapted to receive high frequency oscillations ofvarying frequencies, comprising a primary winding, a secondary windinginductively coupled with said rimary windin and supported fixed relationthereto, an means or varying the inductive relation ofi said windings toac` cord with the frequent4 of the oscillations received, said means inuding a member of magnetiiniblev material mounted for movemember movablein the magnetic field of said windings, and means independent of saidiron member foraccelerating the dis sipation of the Velectrical ca acitycharge upon the primary and secon ary windings upon reversal of cycle ofthe electrical ener impressed upon the transformer.

8 anapparatus of the character de scribed, a hig frequency transformeradapted to receive high frequency oscillations of varymg frequencies,having-a rima winding,l a secondary winding in uctive y coiipled withsaid primary winding, and an iron member movable in the magnetic fieldsof Said windings for varyin the inductive properties thereof, said winings comprising concentrically disposed coextensive coils eachconsisting of a single la er of wire4 whereby to provide small distriuted capacity between the ends thereof.

Intestimony whereof I have hereunto set my hand this 4th day of June,1923.

ORIN E. MARVEL.

CERTIFICATE 0F CORRECTION.

filent No. 1,656,381. Granted January 17, 1928, to

ORIN E. MARVEL.

It le hereby certified that error appears in the printed specificationof the above mmberved patent requiring correction as follows: Page 2,lines 129 and 130, elaim'Z, strike out the words,"disposed within saidbobbin" and insert the lame to follow alter the word "means" in line l,page 3, of the same claim; and that the nid Letters Patent should beread with this correction therein that the same miy conform to therecord of the case in the Patent Oiiice.

Signed and sealed this 14th day ol Fehrnlry, A. D. 1928.

M. J. Moore, Seal. Acting Conmissioner of Patents.

